As a configuration example of a semiconductor chip, for example, JP 2008-130932 A discloses a semiconductor chip having an electrode on its side surface.
FIG. 16 is a cross-sectional view showing a configuration of a conventional semiconductor chip 101 having a side external electrode. The semiconductor chip 101 includes a circuit region 103 formed on a substrate 102, and an electrode pad 104 connected to the circuit region 103. The electrode pad 104 is formed so as to extend to side surfaces of the substrate 102, and functions as a side external electrode.
Such a side external electrode is formed in the following manner. A plurality of circuit regions are formed on a wafer, and conductive portions serving as electrode pads are formed between the adjacent circuit regions. Next, the wafer is partially removed in the region where the conductive portions are formed. Then, a conductive material is filled in the portions where the wafer is removed. Next, the wafer is cut into semiconductor chips, with the filled conductor material attached to the side surfaces of the semiconductor chips. The above-described process forms side external electrodes.
FIG. 17 is a cross-sectional view showing a configuration in which such semiconductor chips are stacked. A first semiconductor chip 111, a second semiconductor chip 112 and a third semiconductor chip 113 are stacked via an adhesive material 114. A side external electrode 115 of each of the semiconductor chips is connected electrically to a side external electrode of another semiconductor chip using a wire 116. With this configuration, it is possible to connect the stacked semiconductor chips electrically to each other without adopting an advanced technology such as a through via.
However, in the above-described configuration, since the side external electrodes are formed on the side surfaces of the semiconductor chips, the sizes of the side external electrodes are small. Therefore, high mounting accuracy is required at the time of arranging the semiconductor chips and connecting the side external electrodes directly.
Further, in the above-described method of forming the side external electrode, it is possible to form only one side external electrode, which is formed on the side surface of the semiconductor chip, in the direction perpendicular to the plane of the semiconductor chip. That is, a plurality of the side external electrodes cannot be arranged in the direction perpendicular to the plane of the semiconductor chip.
Moreover, in the case of making a semiconductor chip having the above-described side external electrode into a semiconductor package, when all of the side external electrodes of the semiconductor chip are made to correspond to electrodes formed on a lower surface (or an upper surface) of the semiconductor package as is usually performed, it is possible to increase the number of electrodes for signals and power sources of the semiconductor chip including side external electrodes, as compared with the case where the semiconductor chip is not provided with the side external electrodes. However, such a configuration increases the number of external connections via the electrodes of the semiconductor package, and hence increases the size of the semiconductor package. Consequently, the size of a semiconductor device having a plurality of the semiconductor packages is increased.